The present invention relates to a light-sensitive composition which is favorably used for preparing, for instance, presensitized plates for use in making lithographic printing plates (hereinafter referred to as "PS plates"), IC circuits and photomasks and in particular to a novel light-sensitive composition improved in sensitivity during exposure to light.
Photo-crosslinkable substances which cross-link through a cyclization-addition reaction have been well-known and have widely been employed as a principal component of a light-sensitive composition for use in making PS plates or the like. Among them, effectively used photo-crosslinkable polymeric compounds are polymers having a maleimido group at a side chain and a polymer having, in the main chain or at a side chain, a cinnamyl, cinnamylidene and/or chalcon group carrying a photodimerizable unsaturated double bond adjacent to an aromatic nucleus. In particular, the polymers having a maleimido group are useful because of their high sensitivity. Examples of a light-sensitive composition containing such polymeric compounds carrying a maleimido group are those disclosed in Japanese Patent Unexamined Publication (hereinafter referred to as "J. P. KOKAI") Nos. Sho 52-988, Sho 52-3055 and Sho 55-160010.
On the other hand, many attempts have been made to use a photopolymerizable light-sensitive composition as a light-sensitive image-forming layer of PS plates or the like. For instance, there have been proposed a basic composition which comprises a polymer serving as a binder, a monomer and a photopolymerization initiator as disclosed in Japanese Patent Publication for Opposition Purpose (hereinafter referred to as "J. P. KOKOKU") No. Sho 46-32714; a composition whose hardening efficiency is improved by the introduction of unsaturated double bonds into a polymer as a binder as disclosed in J. P. KOKOKU No. Sho 49-34041; and a composition in which a novel photopolymerization initiator is employed as disclosed in J. P. KOKOKU Nos. 48-38403 and Sho 53-27605 and U.K. Patent No. 1,388,492. Some of these compositions have already been put into practical use.
However, all of the foregoing conventional light-sensitive compositions do not have sufficient sensitivity and they cannot provide acceptable images when they are exposed to light for only a short period of time.